The present invention generally relates to handling processes and related resources in a distributed operating system.
With a process, in the present connection also called context, is here meant a resource in an operating system which needs to be used by a job for enabling it to execute program code in the process. The process provides the job with several indispensable resources, such as its own program counter, its own memory space, and its own set of processor registers. The process synchronizes jobs by only allowing one job at a time to execute.
By job is here meant, more generally, a phenomenon which is directed towards a process, so that a method in an object owned by the process is executed. A job can create new jobs directed towards other processes or to the own process.
U.S. Pat. No. 3,905,023 illustrates and describes a system including a multiple level operating system. The system is characterized as very big and extraordinarily complicated. The reliability of the system hardware is secured by the capacity of the multiple level operating system to reconfigurate the system modules dynamically and automatically in a suitable way. In all main modules of the system there are error detecting and error reporting circuits providing the operating system with information for performing error analyses and dynamic reconfiguration of the system resources. The memory modules are provided with "single bit" error correcting ability independently of the operating system. The operating system may be regarded as including a basic level and N consecutive levels. The basic level is defined as the core of the operating system. A process in each level of the operating system is responsible for the processes created on the nearmost higher level and not for any other ones. The operating system controls the system resources dynamically and plans job or tasks in a multiple program mixture. It reassigns resources, starts jobs and supervises their execution.
Great Britain Patent Document No. GB 2,079,997 relates to a distributed computer system with a plurality of systems connected to each other. Each one of the systems has a plurality of mutually connected elements. The systems include redundant elements with a distributed operating system for operating, error supervision and reconfiguration of functions while using vertical addressing. When an error is detected, the error is verified, the erroneous element is isolated and its task is assigned to another unoccupied element. If no other element should be available the system is reconfigurated for enabling deteriorated operation while using the available elements.
In U.S. Pat. No. 4,933,936 there is described a distributed computer system providing for flexible error tolerance. A distributed operating system is resident in all computers. Each computer is controlled by a resident copy of a common operating system.